The valence states of Eu ions doped in GaN were investigated by the core-level X-ray and resonant photoemission spectroscopy. Although the photoluminescence spectra show the emissions from only trivalent Eu ions, the existence of both divalent and trivalent Eu ions is suggested by the Eu 3d core-level spectra. Taking into account the results of the 4d-->4f resonant photoemission measurements, it can be concluded that valence transition from Eu3+ to Eu2+ occurs near the surface of GaN. (C) 2002 Elsevier Science B.V. All rights reserved.